Influence of Stagnation Regions on Preconditioned Solutions at Low Speeds

We have examined the effects of different preconditioning definitions on robustness in the vicinity of stagnation regions. Specifically, we have utilized a series of NACA0012 test cases and two different computer codes. Interestingly, the two codes—an in-house research code called GEMS and the wellknown NASA Ames research code ARC2D—are observed to show different degrees of sensitivity to the stagnation region. Based on the studies, we propose a modified definition referred to as local maximum preconditioning, which is shown to maintain robust performance over a range of parametric variations.